SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c88dcc848988c3f5fa7f912afc0b6fe36d72183e41eb5c2908de1858c43c3075' 
  AND token = 'GkzxjwUe0Kg44PCiiznhA4VDP3rLDTFBeQhhPcelqXw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}